Boys will be girls

A 1994 radio program looks at the phenomenon that is creating interest throughout the world's scientific community -the feminisation of males. A beginners guide to understanding endocrine disruption.
"Boys Will Be Girls" on Background Briefing,
ABC Radio National, April 16, 1994.
Reporter: Kirstin Garrett


Last April ABC Radio National Background Briefing broadcast a very comprehensive program on the phenomenon that is creating interest throughout the world's scientific community -the feminisation of males: As new generations are born, the males in many species (including humans) are developing more and more reproductive tract abnormalities, lowered fertility and cancers.

It is being hypothesised that this feminisation of male creatures may be a product of the chemical age. In particular, it is the result of the increasing and pervasive contamination of the environment by man-made chemical compounds that disrupt the endocrine system of the developing embryo. The timing of exposure in the developing organism is thought to be crucial and, although exposure occurs during embryonic development, obvious manifestations may not occur until maturity. Sound familiar?

Kirsten Garrett drew together a number of different aspects of this issue and interviewed key players in the debate, including Sharpe and Skakkebaek and participants of the important "Wingspread Meeting".

It is only in the last 50 years or so that the world has been swamped with a deluge of new chemical compounds. Many of these compounds have been introduced into the environment by human activity and include many that accumulate in body fat, that are in common use, and that are persistent in the environment.

In July 199I a multidisciplinary group of scientists and experts met at Wingspread, Wisconsin, USA, to assess current knowledge on the issue. They concluded that "a large number of man-made chemicals that have been released into the environment have the potential to disrupt the endocrine system of animals, including humans."

A wide range of compounds are now known to have this potential, including DDT, dioxins, herbicides, fungicides, industrial chemicals including those used in the detergent, cosmetics, plastics, paint and lubricants industries, and some metals such as cadmium, lead and mercury.

It is now known that many of these compounds, while not real oestrogen, behave like oestrogen once inside the body. They are sometimes termed "false oestrogens" or "oestrogen mimics". They accumulate in body fat, the body can't flush them out and the cross the placenta to affect the developing embryo.

Dr Theo Colborn of Washington cited laboratory evidence for tills. Just a small amount of dioxin given only once, on day 15, to a pregnant rat resulted in the (adult) male offspring having a 75% sperm count reduction and increased incidence of undescended testes.

The oestrogenic effects of man-made chemicals have been demonstrated in the laboratory and, as the Wingspread conference concluded, the effects are showing up in wildlife populations throughout the world.

The program looked at wildlife studies in different part of the world. Researchers have found that the majority of adult male panthers in an area of Florida had undescended testes, and their bodies were producing excessive oestrogen. These animals were sterile. Alligators in the same area were found not to be developing normally. It was found 20-30% of adult male alligators had shortened and misshapen penises and were sterile.

This appears to be a worldwide phenomena and across species. The point was made that virtually no research has been carried out in the Southern Hemisphere. However research done in the USA, Canada, Scandinavia and the UK shows contaminants have affected the reproductive biology and endocrine systems of birds, fish, reptiles (alligators and turtles), mammals and marine mammals.

A number of years ago Professor John Sumpter and colleagues studied fish in rivers that fed into drinking water catchments in England. It was found that male fish were being feminised -the males were producing an egg-making substance and were showing signs of being hennaphrodite Professor Nils Skakkebaek and Dr Richard Sharpe noted the dramatic decline in the quality of human spenn in recent years, and the alarming increase in rates of undescended testes, prostate and testicular cancer. They hypothesise that these environmental oestrogen mimics may play a role in disrupting embryonic development of the Sertoli cells.

Dr Kate Short in her book Quick Poison, Slow Poison summarises the high health costs of the international pesticide industry and challenges what she terms "the myth of non persistence". She maintains pesticides are very persistent in the environment and studies have indicated that Australians bear a higher body burden of these fat-soluble chemicals than other comparable countries. Many of the pesticides that are routinely used on fruit and vegetables end up in our water supply as well as our food chain.

Unfortunately the technology is not there to test for a)) these substances in our water supply. In one survey of pesticides in Adelaide's water supply, researchers were only able to test for 30% of the known pesticides used in that catchment area.

This debate and interest in the effects of exposure to oestrogenic agents during embryonic development has focused attention back on the DES issue.

A number of researchers, including Sharpe and Skakkebaek, have noted the similarities of the abnormalities appearing in wildlife species with those occurring in DES sons. DES can thus be viewed as a model compound for these other environmental agents with oestrogenic potential.

Dr John McLaughlan of the (US) National Institute of Environmental Health Sciences, stated in the program "The DES-exposed population takes on added importance as leading indicators of what could happen with less potent environmental oestrogens"

However just what this additional and ever increasing load of pervasive environmental oestrogens means for the DES-exposed population is unclear.

T. Colborn & C Clement (Editors) Chemically-induced alterations in sexual and functional development: The wildlife/human connection. Princeton: Princeton Scientific Publishing, 1992
Published in our newsletter DESPATCH in 1994